Process of purifying aluminium.



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" UNITED STATES EDWARD LA I DIV PATENT OFFICE.

OEY ANDERSON, on sT/L Oufs, MISSOURI, ASSIGNOR TO JOHN AM, RUSTEE, OF ST. LOUIS, MISSOURI.

PROCESS OF PURIFYING ALUMINIUM.

SPECIFICATION forming partof Letters Patent No. 716,977, dated December 30, 1902.

Application filed July 27,1901. Serial No- 69,878. (No specimens.) 7 I To all whom it may concern:

Beit known that I, EDWARD LACEYANDER- SON, a citizen of the United States, residing at the city of St. Louis, in the State of Missouri, have invented a certain new and useful Process of PurifyingAlnminium, of which the following is such a full, clear, and exact de cription as will enable any one skilled in th art to which it appertains to practice the same.

All commercial aluminium contains impurities, generallyin the form of silicates of aluminium. Pure aluminium is a bright metal which does not oxidize or tarnish when exposed to air. The impurities or silicates of aluminium tarnish and oxidize in air and give the metal a mottled or dull luster.

The object of my invention is to remove these impurities'from aluminium, so as to produce a metal of bright luster and which does not oxidize or tarnish in the air. My process produces aluminium which shows a surface somewhat like silver, having what is known as a satin finish.

One solution embodying my invention and giving good results is made as follows: To two pounds of nitric acid is added five pounds I of water, the water being added in small quan titles at a time, and when this is cool one pound I said surface durin isallowed to stand about one hour, when The al u miniu rn is the);v placed in the solution and allowed to staii'd'about tentofift'een minutes. At the end of this time the aluminium is taken out and washed with water. It is then ready for use. Apparentlyjnlhense oi this solutigg FglLQfiumic acid and hromic worms Ion metal is p ace 0 In contact witlTthe solution, bubbles of hydrogen are given off. This hydrogen is absorbed by the chromic acid present, with the oxygen of which it enters into combination. Having fully described my invention, what I claim as new, and desire to secure by Letters Patent of the United States, is- I -1. The process of finishing aluminium, which consists in treating the surface thereof with hydrofluoric acid, and removing from g said treatment the gas thereby generated. i

2. The process of finishing aluminium, which consists in treating the surface thereof with hydrofluoric acid, and continuously removing from said surface during said treatment the gas thereby generated.

3. The process of finishing aluminium, which consists in immersing the same in a s0- lution containing hydrofluoric acid, and con tinuously removing from the surface of said aluminium while same is immersed the gas thereby generated.-

4. The process of finishing aluminium, which consists in immersing the same in a solution containing hydrofluoric acid, and continuously removingchemically from the surface of said aluminium while same is immersed the gas generated thereby.

5. The process of treating aluminium,which consists in subjecting the sameto the action of hydrofluoric acid in the presence of a hydrogen absorbent.

6. The process of treatingaluminium,which consists in subjecting the same to the action of hydrofluoric acid in the presence of an oxygen-aifording agent.

7. Theprocess oftreatingaluminium,which consists in subjecting the same to the action of hydrofluoric acid in the presence of chromic acid.

8. The process of treatingaluminium,which consists in subjecting the same to the action of a solution of a metallic fluorid, an acid capable-of decomposing said fluorid, and a hydrogen absorbent.

9. Thepro'cess oftreatingaluminium,which consists in subjecting the same to the action of a. solution of a metallic fluorid, an acid capable of decomposing said fluorid, and a ,chromate of a metal.

10. ma mosets tr treating aluminium, which consists in subjecting the same to the action of-a solution of calcium fluorid, nitric acid, and a. chromate of a metal.

In testimony whereof I have hereunto set my hand and aflixed my seal in the presence of the two subscribing witnesses.

EDWARD LACEI: ANDERSON. [I.. 8.]

Witnesses:

A. O. FOWLER, W. A. ALEXANDER. 

